The effect of the interaction between recrystallization and precipitation on the heterogeneous microstructure and tensile properties in a heavily cold–rolled Al0.3CoCrFeNi high–entropy alloy

Abstract

The present paper focuses on the recrystallization and multiple precipitation behaviors of a heavily cold–rolled Al_0.3CoCrFeNi high–entropy alloy after annealing at temperatures from 700 and 850 °C. Three types of B2 precipitates with different morphologies and sizes form concurrently in the different regions of the microstructure. Post–annealing was also found to increase the fraction of Ʃ3 twin boundaries, which not only refines the austenite, but also facilitates the nucleation for B2 precipitates. The interaction among twins, precipitation and recrystallization plays a crucial role in the formation of the heterogeneous microstructure. As the annealing temperature increases, the yield strength of the alloy decreases while improving the ductility to some extent. Notably, when annealed at 750 °C for 1 h, the alloy demonstrated an optimal balance, exhibiting a yield strength of approximately 1040 MPa and ductility of about 22%. The heterogeneous microstructure triggered multiple strengthening mechanisms, and thus exerts an important effect on the overall tensile properties, along with dislocation slip and twinning–induced plasticity (TWIP) effect.